The present invention relates to a defect inspection device and a defect inspection method, which are capable of inspecting a minute defect present on a sample surface with a high degree of sensitivity.
Thin film devices such as semiconductor wafers, liquid crystal displays (LCDs), or hard disk magnetic heads are manufactured through a number of processing processes. In manufacturing of such thin film devices, for the purpose of yield improvement and stability, an external appearance inspection is performed for each series of processes.
Patent Document 1 (JP 3566589 B1) discloses a method of “detecting a defect such as a pattern defect or an alien substance in corresponding regions of two patterns formed to have the same shape originally based on a reference image and an inspection image obtained using lamp light, laser beams, or electron beams in an external appearance inspection.”
Further, Patent Document 2 (JP 2006-98155 A) discloses “an inspection method capable of deriving an optimal inspection condition by extracting a defect of interest (DOI) efficiently and teaching it in a situation in which a small number of DOIs are included in a large number of nuisances.”
Further, as a technique of improving inspection sensitivity, Patent Document 3 (U.S. Pat. No. 7,221,992) and Patent Document 4 (US 2008/0285023 A) disclose “a method of detecting images according to a plurality of different optical conditions simultaneously, performing a brightness comparison with a reference image for each condition, integrating comparison values, and distinguishing a defect and a noise,” but a problem lies in that a high data transfer rate for transmitting a defect image acquired at a high resolution in each optical condition to a defect determining section is necessary, and a processor of high processing performance for processing images of a plurality of conditions once is necessary.
Patent Document 5 (U.S. Pat. No. 7,283,659) discloses “a method of performing efficient defect classification through two-step determination, that is, classification of defect candidates by a non-image feature such as process information and classification by a defect image feature.”
Patent Document 6 (JP 2012-112915 A) discloses a method of extracting a defect candidate from each of images detected in a plurality of imaging conditions, extracting a detailed feature quantity by processing a narrow region image centering on a defect candidate in any one condition or all imaging conditions based on a determination result obtained by integrating feature quantities obtained by processing respective images, and determining a defect based on the feature quantity.